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Biomedical subjects

H Hamilton

Publications and source records attributed to H Hamilton.

At least 37 records · Page 2Linked to original sources
PubMed1996

The characteristics and intervention histories of incarcerated and conduct-disordered youth.

OBJECTIVES: 1) To determine if incarcerated youth and conduct-disordered youth in treatment display similar risk factors associated with chronicity of antisocial behaviour; 2) to determine if incarcerated youth had experienced high numbers of interventions by many different agencies as has been reported for conduct-disordered youth in treatment. METHOD: The files of 25 conduct-disordered youth in treatment and 25 incarcerated youth were examined to extract all relevant data. RESULTS: Incarcerated youth were similar to conduct-disordered youth with regard to the number of symptoms of disruptive behaviour disorders, age of onset of behavioural problems, and family backgrounds. Both groups had high numbers of interventions and agencies in their histories. Interventions began earlier for the conduct-disordered youth. CONCLUSION: The distinction between conduct-disordered youth who are treated and youth who are incarcerated may be arbitrary and accidental. Given the similarity in the clinical characteristics, incarcerated youth should be offered help that is similar to that offered to conduct-disordered youth. Such help may lower the rate of recidivism.

Adolescent↗
PubMed1996

DNA profiling in two Alaskan Native populations using HLA-DQA1, PM, and D1S80 loci.

Two Native Alaskan populations were sampled and DNA profiles were generated for 201 individuals. Ninety two blood samples were collected from the North Slope Borough region of Alaska and the remaining 109 blood samples came from Native Alaskans in the Bethel and Wade Hampton areas. Allele and genotype frequencies were established for the HLA-DQA1, LDLR, GYPA, HBGG, D7S8, Gc, and D1S80 loci. Native Alaskans are slightly less polymorphic than Caucasians at the HLA-DQA1 locus. In contrast, the PM loci appear to be nearly as informative in the Native Alaskan populations as in Caucasians for identity testing. The data clearly demonstrate that all the loci tested are highly informative for the Alaskan populations and fall well within Hardy-Weinberg expectations. There is little evidence for departure from expectation of independence of alleles across loci. The data demonstrate that estimates of multiple locus profile frequencies can be obtained from Native Alaskan populations using the product rule under the assumption of independence of loci. In addition, Native Alaskan databases were more similar to each other and to other Native American databases than they were to U.S. Caucasians and African Americans.

Alaska↗
PubMed1995

Effect of eradication of Helicobacter pylori infection on gastric epithelial cell proliferation.

Helicobacter pylori infection has been linked with gastric carcinoma. Epithelial cell proliferation is an indicator of cancer risk. The aim of this study was to assess gastric epithelial cell proliferation before and after eradication therapy and to assess the efficacy of treatment of H. pylori infection using lanzoprazole and clarithromycin. Twenty-three patients with H. pylori-associated gastritis were treated with lanzoprazole 30 mg daily for four weeks and clarithromycin 500 mg three times a day for two weeks. Antral mucosal biopsies were taken for gastric epithelial cell proliferation analysis using the in vitro bromodeoxyuridine (BrdU) immunohistochemical technique before and four weeks after eradication therapy. Labeling index percent (LI%) was calculated as the percent ratio of proliferating cells to the total number of cells in the gastric pit. Efficacy of treatment was assessed in 16 subjects. Eight were negative for H. pylori infection 28 days after therapy and in eight patients H. pylori infection was not eradicated. The eradication rate for the regime was 50%. Cell kinetics were assessed in 19 subjects who completed treatment. Patients with H. pylori infection had a significantly higher LI% compared to normal (N = 19, LI%: 5.01 +/- 0.3 vs 3.2 +/- 0.2, N = 29). Eradication of H. pylori infection significantly reduced epithelial cell proliferation (N = 9, LI%: 5.2 +/- 0.4 to 3.2 +/- 0.8, P < 0.001), whereas it was unaltered in those whose infection was not eradicated (N = 10, LI%: 4.8 +/- 0.4 to 5.5 +/- 0.5, P = 0.18).(ABSTRACT TRUNCATED AT 250 WORDS)

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1995

Comparison of molecular and microscopic techniques for detection of Treponema pallidum in genital ulcers.

We compared the ability of direct immunofluorescent staining (DFA) and the PCR to detect Treponema pallidum in specimens from patients with genital ulcer disease. Touch preparations from 156 patients with genital lesions were fixed in acetone and stained with a fluorescein-labeled monoclonal antibody specific for the 37-kDa antigen of T. pallidum. After microscopic examination, the smear was removed from the slide with a swab. DNA was extracted with phenol-chloroform and precipitated with isopropanol. Ten microliters of the extracted DNA was amplified by PCR using primers for the gene encoding the 47-kDa protein of T. pallidum and hybridized to an internal probe. Twenty-two of 156 specimens were positive for T. pallidum by DFA and PCR, while 127 were negative by both methods, yielding a concordance of 95.5% (kappa = 0.84). Four specimens were positive by PCR and negative by DFA, while three specimens were negative by PCR and positive by DFA. The DFA-negative, PCR-positive specimens may have resulted from the presence of large numbers of leukocytes on the slides, obscuring visualization of treponemes. The DFA-positive, PCR-negative results were not due to inhibition of the PCR since purified T. pallidum DNA was amplified when added to aliquots of these specimens. Negative results in these specimens were most likely due to inefficient recovery of their DNA. These data suggest that DFA and PCR are equivalent methods for detection of T. pallidum on touch preparations of genital lesions. Further refinements of the PCR assay are necessary for it to significantly improve the detection of T. pallidum in genital lesions.

Antigens, Bacterial↗
PubMed1995

Ventilatory stability to CO2 disturbances in wakefulness and quiet sleep.

Oscillatory ventilatory pattern occurs more frequently in sleep despite the stabilizing factor of sleep-induced reduction in CO2 chemosensitivity. In nine young normal humans, we have tested the hypothesis that, despite a sleep-induced reduction in chemosensitivity, the transient central chemoreceptor-mediated change inspiratory ventilation (VI) caused by a standardized disturbance to chemoreflex ventilatory control is similar in quiet sleep and wakefulness. The equivalent VI response to a single-breath hyperoxic hypercapnic stimulus (i.e., inhaling a single breath of 0.01 liter of CO2 in O2--a direct measure of "closed-loop" dynamic response) was determined using pseudorandom binary CO2 stimulation and the prediction-error method of transfer function estimation. From these data, the response of VI to a single-breath increase of 1 Torr in end-tidal PCO2 was also derived, from which "dynamic" central chemosensitivity was calculated. Despite a 43% reduction in dynamic central chemosensitivity, the peak and the area under the closed-loop VI response are similar in wakefulness and quiet sleep, whereas sleep increases the duration of the response by 48%. Thus hyperoxic ventilatory stability is not reduced in quiet sleep relative to wakefulness. We propose that changes in dynamics of pulmonary gas exchange in sleep substantially offset the decreased chemosensitivity, thereby maintaining the gains and time constants of the central chemoreceptor-mediated component of the closed-loop ventilatory control system similar to those during wakefulness.

Adult↗
PubMed1995

Recrudescence of Helicobacter pylori infection in patients with healed duodenal ulcer after treatment with different regimens.

OBJECTIVE: To determine the 12-month posttherapy recurrence (recrudescence) of Helicobacter pylori in patients with healed duodenal ulcer after apparent eradication of the organism with anti-H. pylori treatment. The influence of original anti-H. pylori treatment regimens on the recrudescence was also evaluated. METHODS: One hundred and ninety patients who had duodenal ulcer healed and H. pylori eradicated (as assessed by four routine techniques 4 wk after the end of anti-H. pylori therapy) with one of five regimens were studied. The five regimens were: 1) colloidal bismuth subcitrate (CBS) 120 mg; 2) CBS plus amoxicillin (500 mg); 3) CBS plus metronidazole (400 mg); 4) CBS plus metronidazole and amoxicillin; and 5) CBS plus metronidazole and tetracycline (500 mg). CBS was taken four times daily for 4 wk, and antibiotics were taken three times daily for the first week. The patients were re-endoscoped, and the status of H. pylori, duodenal ulcer, and gastritis was assessed after a period of follow-up (mean 14 months after commencement of treatment). RESULTS: H. pylori infection recurred in 36 (18.9%) of these patients. Recrudescence rate with monotherapy was 47.1%, with dual therapy 29.2-35% and with triple therapy 9.2-14.3%. Nineteen (52.7%) of the 36 patients with recrudescent infection had ulcer relapse, and the rate for H. pylori-negative patients was 3.2% (5/154). CONCLUSION: Recrudescence of H. pylori infection after apparent eradication can occur, but it could be that the treatment was only suppressing the organism. The definition of eradication of H. pylori infection may need to be revised, and more sensitive techniques to assess eradication of H. pylori are required.

Adult↗
PubMed1994

Reduction of red cell glucose transporter intrinsic activity in diabetes running.

The function of the red blood cell glucose transporter was compared in samples from subjects with and without diabetes. Activity of the glucose transporting protein (GLUT-1) was measured by determining the first order rate constant for uptake of sorbose, a sugar transported by GLUT-1. Red cells were isolated from 13 patients with diabetes and 9 patients without diabetes and were washed free of intracellular glucose. The uptake rate constant was calculated from measurements of sorbose uptake at 0, 1, 2, 5 and 90 minutes at 37 degrees C. The rate constant was significantly decreased in cells isolated from patients with diabetes (0.242 vs 0.303 min-1 in non-diabetic subjects, p < 0.005). The number of GLUT-1 present per mg of membrane protein and clinical parameters such as weight, age, serum cholesterol and urea nitrogen were not significantly different between the groups. The rate constant per pmol of GLUT-1 was significantly decreased in the diabetic subjects. The relationship between diabetes control and the rate constant was not linear and there was no relationship between the calculated intrinsic activity and the HA1c. Because red cell GLUT-1 are not translocated and red cells do not synthesize new proteins, these data suggest that the intrinsic function of the glucose transporter from red cells of patients with diabetes is diminished. This may be due to alterations in the transporter or its membrane environment.

Adult↗
PubMed1994

Continuity of care for conduct disordered youth.

The objectives of this study were to determine which risk factors associated with chronicity had been displayed by youths who had been treated for conduct disorder in a tertiary level mental health centre and also to count the number of interventions and the number of agencies involved during their many years in treatment. The files of 25 youths with conduct disorder were examined to extract all relevant data. The youths averaged nine years between first intervention and last discharge. Common risk factors were the early onset and the variety of antisocial behaviours and the multiple settings in which behaviours occurred. The youths experienced an average of 19 interventions by 15 agencies. Interventions lasted on average seven months with little occurrence of follow-up. The severity of antisocial behaviours increased from first to last intervention. The apparent ineffectiveness of treatment may be related to the short duration of treatments and the lack of follow-up which resulted in the involvement of many agencies.

Adolescent↗
PubMed1993

Effects of administration of anti-CD4 and anti-CD8 monoclonal antibodies on Mycobacterium paratuberculosis infection in intragastrically challenged mice.

In this study, we examined the roles of CD4+ and CD8+ cells in resistance to experimental paratuberculosis. Mice received purified anti-CD4 or anti-CD8 monoclonal antibodies before intragastric challenge with Mycobacterium paratuberculosis and on a biweekly basis for six months. This resulted in sustained depletion of CD4+ and CD8+ cells as verified by flow cytometry analysis of spleen cells from M. paratuberculosis infected mice. Depletion of CD4+ or CD8+ cells did not enhance fecal shedding of M. paratuberculosis, bacillary multiplication in the liver and ceca, nor histopathologic damage to the intestinal tract, mesenteric lymph nodes, spleen and liver. These data suggest that cells other than CD4+ or CD8+ cells are important for host defense in experimental paratuberculosis.

Animals↗
PubMed1993

Short report: treatment of Helicobacter pylori-associated duodenal ulcer with omeprazole plus antibiotics.

Omeprazole heals most duodenal ulcers after 4 weeks of treatment but relapse is common. Eradication of Helicobacter pylori is associated with reduced rate of ulcer relapse. This study investigates the effect of omeprazole with antibiotics in H. pylori-associated duodenal ulceration. Forty-three patients with endoscopically proven duodenal ulcer and H. pylori entered this study. Treatment consisted of 20 mg omeprazole daily (four weeks) and seven days (first week) treatment with 400 mg metronidazole t.d.s. and 500 mg tetracycline t.d.s. Four weeks after completing the treatment, 81% (35/43) had a healed duodenal ulcer, and 58% (25/43) had H. pylori eradication. In those who healed, at one year 21 remained H. pylori-negative, 12 had persistent H. pylori infection and 2 had re-infection. The ulcer relapse rate at one year was 26%: of the 9 who relapsed, 6 had persistent infection, 2 were re-infected, and only 1 was H. pylori-negative. This combination therapy of antibiotics with omeprazole successfully eradicates Helicobacter pylori and has a lower ulcer relapse than omeprazole alone.

Adult↗
PubMed1993

Cefprozil versus penicillin V in treatment of streptococcal tonsillopharyngitis.

In a randomized multicenter study, the efficacy and safety of cefprozil were compared with those of penicillin in the treatment of group A streptococcal tonsillopharyngitis in children. Of the 409 patients enrolled, 323 were evaluable for their clinical and bacteriological responses; of these 323 children, 172 received cefprozil and 151 received penicillin V. The clinical responses in patients treated with cefprozil were significantly better than those in patients who received penicillin (95.3 versus 88.1%; P = 0.023). Eradication of the original serotype of group A streptococci was achieved in 91.3% of patients treated with cefprozil and 87.4% of patients treated with penicillin, the difference not being statistically significant (P = 0.125). However, there were significantly more symptomatic patients among the bacteriological failures in the penicillin group (68.4%) than in the cefprozil group (26.7%). beta-Lactamase-producing Staphylococcus aureus was more frequently isolated from the throat flora during penicillin therapy than during cefprozil treatment. No difference in the incidence of adverse events probably related or of unknown relationship to the study drugs was observed in the two treatment groups (5.2% of those treated with cefprozil and 6.0% of those treated with penicillin). Cefprozil can be considered a safe and reliable drug for the treatment of streptococcal pharyngitis in children.

Cephalosporins↗
PubMed1993

Effects of vitamin antioxidant supplementation on cell kinetics of patients with adenomatous polyps.

Colonic crypt cell proliferation is used as an indicator of risk of colorectal carcinoma. Subjects with adenomatous polyps and cancer have an increased cell proliferation and a shift of the proliferative zone towards the apex of the crypt. Epidemiological and in vitro studies have confirmed a link between vitamins A, E, C, beta-carotene, and colorectal cancer. In vitro bromodeoxyuridine immunohistochemical technique was used to assess the effect of daily oral supplementation with vitamin E (160 mg), vitamin C (750 mg), or beta-carotene (9 mg) on the colonic crypt cell proliferation in patients with adenomatous polyps (n = 40) compared with normal subjects with no colonic disease (n = 20). The patients were given supplementation for one month and colonic biopsy specimens were taken before and at the end of the trial. Patients with adenomatous polyps had a significantly higher mean labelling index per cent than controls (p < 0.001). Vitamin C or beta-carotene supplementation, however, significantly reduced the total proliferation (p < 0.005) whereas vitamin E supplementation had no effect on the colonic crypt cell proliferation. beta-carotene reduced cell proliferation at the base of the crypt only. Vitamin C reduced cell proliferation in all the crypt compartments from the apex to the base to those values seen in age and sex matched controls. These findings indicate that prolonged supplementation with vitamin C may reduce the recurrence of adenomatous polyps.

Adenoma↗
PubMed1993

Pattern of breathing and upper airway mechanics during wakefulness and sleep in healthy elderly humans.

Elderly subjects are known to be prone to periodic breathing in sleep. Because periodic breathing may be associated with changes in upper airway caliber, we hypothesized that oscillations in upper airway caliber contribute to the increased prevalence of sleep-related periodic breathing in the elderly. We tested this hypothesis by measuring upper airway resistance, ventilatory variables, and the pattern of variation of these variables in groups of body size-matched young and elderly healthy individuals during wakefulness and stage 2 non-rapid-eye-movement sleep. No major differences existed between the two groups during either wakefulness or sleep in mean upper airway resistance or ventilation values. However, ventilation was more variable during sleep in the elderly; this variability was oscillatory in the majority of elderly subjects at an average rate of 0.04 breaths/cycle or one cycle approximately every 24 s. Oscillations in upper airway resistance during sleep were associated with reciprocal oscillations in tidal volume and/or minute ventilation at the same frequency. Those subjects who had significant oscillations in upper airway resistance had more apneas and hypopneas than those subjects without such oscillations. Oscillations in resistance and ventilation occurred in the supine but not in the lateral body position. We conclude that the wide oscillations in upper airway resistance present during sleep in supine healthy elderly subjects produce a fluctuating mechanical limitation of ventilation, which may contribute to periodic breathing.

Adult↗
PubMed1993

Mechanism of sleep-induced periodic breathing in convalescing stroke patients and healthy elderly subjects.

Cerebral vascular ischemic strokes are known to precipitate Cheyne-Stokes periodic breathing. Interestingly, Cheyne-Stokes-like breathing during sleep may be associated with obstructive sleep apnea (OSA) in some individuals. Therefore, it was reasoned that stroke patients with periodic breathing in sleep would be susceptible to OSA. Because oscillations in upper airway resistance can occur as a component of sleep-induced periodic breathing, we hypothesized that stroke patients with sleep-induced periodic breathing would have oscillations in upper airway resistance. These oscillations in resistance would be expected to contribute to OSA. We studied stroke patients with sleep-induced periodic breathing and control subjects to evaluate the relationship between upper airway resistance and ventilation in periodic breathing in sleep. Ventilation and upper airway resistance were measured in presleep wakefulness and in stage 2 NREM sleep. Mean tidal volume, minute ventilation, respiratory cycle timing variables, and upper airway resistance were not different between stroke and control subjects, either awake or asleep. Upper airway resistance increased and ventilation volume decreased from wakefulness to sleep in both groups. In an equivalent number of subjects from each group, reciprocal patterned oscillations in tidal volume and upper airway resistance were present at a 5 to 12.5 breath frequency during sleep. As upper airway resistance increased, tidal volume decreased. Stroke patients had wider fluctuations in upper airway resistance than control subjects, likely contributing to the higher number of sleep-disordered breathing events observed in the stroke patients.

Aged↗
PubMed1989

Linguistic encoding in short-term memory as a function of stimulus type.

In this study, we investigated bases for encoding linguistic stimuli in short-term memory. Past research has provided evidence for both phonological (sound-based) and cherological (sign-based) encoding, the former typically found with hearing subjects and the latter with deaf users of sign language. In the present experiment, encoding capabilities were delineated from encoding preferences, using 58 subjects comprising six groups differing in hearing ability and linguistic experience. Phonologically related, cherologically related, and control lists were presented orally, manually, or through both modalities simultaneously. Recall performance indicated that individuals encode flexibly, the code actually used being biased by incoming stimulus characteristics. Subjects with both sign and speech experience recalled simultaneous presentations better than ones presented orally or manually alone, which reveals the occurrence of enhanced encoding as a function of linguistic experience. Total linguistic experience appeared to determine recall accuracy following different types of encoding, rather than determining the encoding basis used.

Adult↗
PubMed1986

Prediction of bone marrow iron findings from tests performed on peripheral blood.

After evaluating multiple tests, the authors have devised a scheme to predict bone marrow iron findings from tests performed on peripheral blood. They examined bone marrows from 97 consecutive patients with anemia who were divided into five marrow morphologic groups: (1) iron deficiency; (2) anemia of chronic disease; (3) abnormal sideroblasts; (4) ring sideroblasts; and (5) other. Tests of peripheral blood included hemoglobin, hematocrit, red blood cell count and red blood cell indices, reticulocyte count, sedimentation rate or zetacrit, ferritin, iron, iron binding capacity, free erythrocyte protoporphyrin, and tests of hepatic and renal function. Cluster analysis, multidimensional scaling, and logistic discriminant analysis were used to derive a graph of serum ferritin with the sedimentation rate, allowing accurate confirmation or exclusion of iron deficiency in most patients. Percent saturation of serum transferrin and serum ferritin allowed identification of only 50 percent of patients with abnormal or ring sideroblasts while excluding 100 percent of patients without abnormal or ring sideroblasts. In three years of follow-up, two of 19 patients with abnormal or ring sideroblast have developed the dysmyelopoietic syndrome or ANLL, respectively. With the aid of the two parameter graphs described, the authors believe the differential diagnosis of the hypoproliferative anemias relating to iron metabolism can frequently be made without examination of the bone marrow.

Anemia↗